Firaxis developer Alex "alexman" Mantzaris has posted a fix for the Mehmed II leaderhead crashing Civ4 Warlords for certain graphics cards problem. If you experience this problem, you can get the fix here.

To install, unzip it to your Warlords\Assets\Art\Leaderheads\MehmedII folder (overwrite existing files after backing up, and undo any XML changes you made to LeaderheadInfos.xml).

Thanks will attempt.